1. Field
This disclosure relates to a method of manufacturing a laminated core and, more specifically, to a method of manufacturing a laminated core constituted by combining core pieces of equal to or more than two different shapes.
A laminated core is a component of a motor. The laminated core is formed by stacking a plurality of core pieces each of which is processed in a predetermined shape, and fastening the pieces together. The motor includes a rotor and a stator each of which contains a laminated core, and is produced through a step of winding a coil on the stator and a step of attaching a shaft to the rotor, for example. Motors incorporating laminated cores have been conventionally used as driving sources for appliances, such as a refrigerator, an air conditioner, a hard disc drive, and an electric tool, and are also used as driving sources for hybrid cars in recent years.
A progressive die is commonly used for manufacturing a laminated core. In this progressive die, core pieces are serially stamped out from a belt-like core material, and a plurality of core pieces are stacked until a predetermined lamination thickness is obtained. The thickness of a laminate discharged from the progressive die is required to be within a tolerance depending a the thickness of a laminated core to be produced. However, the thickness of the belt-like core material is not necessarily uniform, in other words, there are variations in thickness. Thus, the thickness of the laminate may not be within a tolerance because of effects of variations in thickness when a predetermined number of core pieces are simply laminated.
2. Related Background Art
Japanese Unexamined Patent Publication No. 52-156305 discloses a device with which laminated cores having a constant thickness are obtained regardless of variations in thickness of core pieces by measuring the thicknesses of the core pieces to be laminated in advance and controlling a stamping device on the basis of the measured data.
Japanese Unexamined Patent Publication No. 11-55906 discloses a method of manufacturing a counterbored laminated core, in other words, a laminated core constituted by combining core pieces of equal to or more than two different shapes. In the manufacturing method disclosed in Japanese Unexamined Patent Publication No. 11-55906, a control program is used that corrects the number of sheets to be laminated by specifying one of counterbores except for counterbores with which the number of sheets to be laminated is specified. A laminated core constituted by combining core pieces of equal to or more than two different shapes is not limited to counterbored laminated cores, and another example is a laminated core internally having a flow path for a refrigerant (see Japanese Unexamined Patent Publication No. 2010-263757).